Problem in Netware 5.1 with Disk IBM EXP300

I have a Novell 5.1 Netware Server (IBM XSERIES 360). with Support
Pack revision 6, this server is connected with a EXP300 IBM sytem storage
disk. The machines with windows OS get hanged when we open windows
explorer to open a file, even when we try to delete the file that hanged
our machine throught the X- SERVER-Grafical Console, we can??t do it. ?? We
try to restart this server with the command "down", but it doesn??t
work,and then we have to disconnect from electrical net pressing the power
button. When we restart the server all works ok, and this failure
ocurrs .